1. Field of the Invention
The present invention relates to a dual band antenna unit for a mobile device, and more particularly, to a dual band antenna unit for a mobile device, in which antennas for different frequency bands are united in a single antenna unit.
2. Background of the Related Art
Generally, a mobile device is a mobile telecommunication apparatus having a variety of functions, such as wireless communication, network connections, or digital broadcast reception. The mobile device has an antenna for improved wireless communication. The antenna is used in sending or receiving radio frequency waves for wireless communication. The antenna is formed according to a desired frequency and/or wavelength. For effective antenna operation, the antenna can only resonate at one particular frequency.
Recently, the trend is for mobile devices to move towards miniaturization as well as multifunction, for example wireless communication, wireless Internet communication, navigation, digital broadcast reception, or Bluetooth communication. Accordingly, various frequency bands may be specified and a plurality of frequency bands may be utilized in a mobile device.
As mobile devices utilize more frequency bands, the mobile devices require more antennas corresponding to more frequency bands. As a result, the size of mobile devices may increase.
A solution has been suggested to use only one antenna for the adjacent frequencies. However, it is difficult to use only one antenna for non-adjacent frequencies and frequency bands, and as a result different antennas are used corresponding to different frequency bands.
A conventional mobile device has different antennas for transmitting communication signals of different frequency bands. Take for example, a mobile device that provides digital broadcast service and Bluetooth® (hereinafter, “Bluetooth”, a short range radio communication technique) service. The frequency band of Bluetooth is 2.4 GHz, whereas the frequency band of Satellite Digital Multimedia Broadcasting (S-DMB) is 2.63 to 2.655 GHz, and the frequency band of Terrestrial DMB (T-DMB) is 174 to 240 MHz and 1.452 to 1.492 GHz. The difference in frequency bands between Bluetooth signals and DMB signals requires the mobile device to have different corresponding antennas.
Further, an antenna for DMB and an antenna for Bluetooth are installed at different locations in a mobile device, causing an antenna mounting space to occupy a considerable portion of the mobile device, thus failing in miniaturization of the mobile device. Further, this may result in a complicated process for producing a mobile device.